Recently, R. Palanivel et al. investigated the role that RhoA-mediated re-organization of the actin cytoskeleton has in adiponectin-regulated glucose uptake in cardiomyocytes.  Adiponectin is a protein secreted by adipose tissue that modulates glucose and fatty acid metabolism.  In concert with APPL1, an adiponectin receptor binding partner, adiponectin carries out these functions which are important in obesity and type 2 diabetes, two diseases that reduce cardiac energy metabolism. The authors found that adiponectin (both full-length and globular) elevates RhoA activity which correlates with increased actin polymerization and glucose uptake.  Changes in the G-/F-actin ratio likely involve APPL1 as adiponectin increases colocalization of actin and APPL1.  Inhibition of actin polymerization or RhoA signaling significantly reduces the adiponectin-mediated increase in glucose uptake.  Thus, RhoA-mediated actin cytoskeleton remodeling is required for adiponectin-regulated glucose uptake in cardiomyocytes.  Increased glucose uptake is cardioprotective in diabetes. A number of products by Cytoskeleton Inc. (“The Protein Experts”) were essential in this study, providing accurate and sensitive assays for quantifying levels of activated RhoA and changes in G- and F-actin levels or binding partners in cardiomyocytes under conditions of RhoA inhibition.

• RhoA G-LISA activation assay 
• G-/F-actin In Vivo Assay Kit
• Anti-actin antibody
• Cell-permeable Rho inhibitor

These reagents are available in Europe through tebu-bio, who have also compiled useful selection tools:

• Actin Product Guide

• Small G Protein Product Guide

Reference: Palanivel et al. 2014. Adiponectin stimulates Rho-mediated actin cytoskeleton remodeling and glucose uptake via APPL1 in primary cardiomyocytes. Metabolism. 63, 1363-1373.

Cell culture under oxygen controlled conditions: an improvement towards more predictive results

Oxygen concentration in tissues is a key factor for cell and organ survival. In normal conditions, partial oxygen pressure (pO2) results in the balance between oxygen delivery and its consumption. Oxygen is transported, in mammals, by circulating red blood cells. Partial oxygen pressure in tissues varies widely, depending on their respective metabolic requirements and their functional status. In normal physiological conditions,  partial oxygen pressure is called physioxia. Any alteration of tissue environment leading to a decrease in partial oxygen pressure is called hypoxia. Hypoxic conditions have been observed in many different pathological situations like tumor development, obesity or transcient ischemia.

Kv1.3 channels are expressed in T-cell lymphocytes and over-expressed in autoimmune diseases. They can be see as a therapeutic taget for T cell mediated autoimmune diseases.

As part of the innate immune response, Toll-like receptor 9 recognizes unmethylated CpG nucleotide sequences, which are very common in viruses and prokaryotes and more rare in vetebrates. Scientists routinely use synthetic oligonucleotides as TLR9 agonists for a variety of applications requiring activation of an innate immune response via TLR9. These relatively simple oligonucleotides are easy to produce, and as a result some companies have extensive catalog offers.

TLR9 structure in complex with CpG ODN. Source: Zhou et al. doi:10.1186/1742-4682-10-18.